The embodiment relates to a lens unit, a manufacturing method of the same, and a camera module including the same.
Recently, a camera module has been installed in a mobile communication terminal, an information technology (IT) device, such as a PDA or an MP3 player, a vehicle, and an endoscope. As the technology has been developed toward the high-pixel camera module from the conventional VGA camera equipped with 0.3 mega pixels, the camera module has been manufactured in a small size with a slim structure according to targets to which the camera module is installed. In addition, the camera module has been equipped with various additional functions, such as auto-focusing or optical zoom functions, at the low manufacturing cost.
Meanwhile, the camera module manufactured in these days is equipped with an image sensor module, which is manufactured through a COB (chip of board) scheme, a COF (chip of flexible) scheme or a CSP (chip scale package) scheme, and is usually connected to a main substrate through an electric connection unit, such as a PCB (printed circuit board) or an FPCB (flexible printed circuit board).
However, users recently request the camera module, which can be directly mounted on the main substrate similar to a general passive element, in such a manner that the manufacturing process for the camera module can be simplified while reducing the manufacturing cost.
The camera module is generally manufactured by attaching an image sensor, such as a CCD or a CMOS, to a substrate through the COB scheme or the COF scheme. An image of a subject is focused by the image sensor and the focused image is stored as data in a memory, which is installed inside or outside the camera module. In addition, the stored data are converted into electric signals and the electric signals are displayed as images through a display medium, such as an LCD or a PC monitor provided in a device.
A camera module according to the related art includes a housing, an image sensor supported on a bottom of the housing to convert an image signal received through a lens into an electric signal, a lens group to focus an image signal of a subject to the image sensor, and a barrel in which the lens group are stacked. The housing, the lens group and the barrel are sequentially coupled with each other.
In addition, an FPCB mounted thereon with chip components, which are electric components serving as a condenser and a resistor to drive the image sensor including a CCD or a CMOS, is electrically connected to the bottom of the housing.
In the camera module having the above structure according to the related art, in a state that a plurality of circuit components have been mounted on the FPCB, an ACF (anisotropic conductive film) is inserted between the substrate and the image sensor, and heat and pressure are applied thereto in such a manner that the substrate, the image sensor and the ACF are fixedly bonded and electrically connected with each other and an IR cut-off filter is attached to an opposite side.
In addition, in a state that the barrel provided therein with a plurality of lens groups is temporally screw-coupled with the housing, as described above, the assembled FPCB is fixedly bonded to the bottom of the housing by an adhesive.
Meanwhile, after the FPCB, to which the image sensor is attached, has been fixedly bonded to the housing coupled with the barrel, a focus adjustment is carried out with respect to a subject (resolution chart) located in front of the barrel and spaced apart from the barrel by a predetermined distance. At this time, the focus adjustment of the camera module can be achieved between the lens group and the image sensor while adjusting the vertical displacement by rotating the barrel screw-coupled with the housing.